freecalypso-docs: Quadband-ideas annotate

annotate Quadband-ideas @ 23:14391ad53281

FCDEV3B-repackaging article removed for legal reasons The idea expressed in that article, namely the idea that some party other than Mother Mychaela could be permitted to create a derived work based on FCDEV3B board design and have it be accepted into the FreeCalypso family, is no longer allowed by our current stance on the matters of intellectual property, particularly Falconia IP. For technical content, the new FC-modem-family and Quadband-ideas articles should fully supplant this old FCDEV3B-repackaging article.

author	Mychaela Falconia <falcon@freecalypso.org>
date	Wed, 23 Oct 2019 00:43:21 +0000
parents	3fa4006696d0
children	00216b7cfc4d

rev	line source
20 3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	1 Our current Openmoko-based Calypso+RF modem core is very very good, but it has
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	2 one shortcoming compared to TI's Leonardo+ reference design: it is triband
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	3 rather than quadband. This triband restriction stems from OM's use of discrete
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	4 antenna switch and SAW filter components as opposed to an integrated FEM (front
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	5 end module) like on Leonardo+. In addition to the band restriction, our current
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	6 triband RF design suffers from one other very unpleasant problem: we have no
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	7 datasheet for the antenna switch component which we have to use. We know from
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	8 Openmoko's BOM data that the manufacturer is Darfon and that the part number for
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	9 this antenna switch component is ASM4532T0P06-1, we are able to buy this part
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	10 from our Chinese grey market suppliers, we build our boards with these parts and
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	11 our boards do work perfectly fine when we get a good batch, but we have to do
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	12 this entire process blindly, without any datasheet or other documentation for
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	13 this mystery part.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	14
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	15 This article outlines some ideas for how we may be able to move from this RFFE
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	16 to a different one, replacing our current mystery antenna switch with something
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	17 less mysterious and better documented, and improving our radio capability from
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	18 triband to quadband at the same time.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	19
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	20 Epcos M034F
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	21 ===========
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	22
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	23 TI's Leonardo+ and E-Sample boards used a magic component made by Epcos (the
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	24 canonical SAW filter manufacturer during that era) called M034 or M034F (the
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	25 exact proper designation is unclear). It was an integrated quadband FEM,
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	26 integrating the antenna switch and SAW filters in one component package, with a
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	27 special twist. The special twist is that even though there are 4 separate Rx
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	28 band SAW filters inside that M034 "chip" module, corresponding to its advertised
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	29 quadband capability, only 3 Rx signal path differential pairs come out of it,
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	30 neatly corresponding to the 3 LNA inputs on TI's Rita transceiver. This twist
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	31 is important because even though the Rita transceiver itself is fully quadband
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	32 internally, it has only 3 LNA inputs, with GSM850 and EGSM bands sharing the
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	33 same LNA input while each of DCS and PCS get their own.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	34
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	35 We do have an M034F.pdf datasheet for this magic component (came along with
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	36 Calypso and Leonardo docs), and the block diagram on page 6 shows the magic
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	37 quite clearly: there is a baseband-controlled switch selecting between EGSM Rx
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	38 and GSM850 Rx (in addition to the two usual Tx switches), this switch directs
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	39 the low band Rx path toward one of two different SAW filters, and the outputs
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	40 of those two filters are then joined. The high band Rx path always goes to both
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	41 DCS and PCS band SAW filters (I assume it is a 50/50 split of the total incoming
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	42 energy, with each path suffering by 3 dB as a result), and each of those high
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	43 band Rx SAW filters gets its own output going to its own dedicated Rita LNA
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	44 input.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	45
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	46 I (Mother Mychaela) would absolutely love to play with an M034-based quadband
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	47 Calypso+Iota+Rita board in my lab with the trusty CMU200 instrument, and to see
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	48 how well it actually performs, especially in comparison with our current
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	49 OM-based triband version. However, in all of my years of searching I have never
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	50 found a physical Leonardo board (any version), nor have we ever found any
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	51 Leonardo PCB layout files which would allow us to build a modern recreation -
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	52 thus the magic of M034 remains elusive.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	53
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	54 Unless a miracle happens and we are able to obtain either a physical Leonardo+
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	55 board or a PADS PCB file for one, there is no quick or low-effort way to "just
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	56 try" this M034 RFFE. Instead if we wish to build a FreeCalypso board with this
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	57 RFFE, it would have to be "the full 9 yards": a full-blown PCB design and layout
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	58 effort. There is no way to just "drop" the M034 into our existing PCB design
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	59 in the place of our current triband RFFE, it would have to be either a very
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	60 disruptive RF section layout change or an entirely new PCB layout, making this
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	61 idea very open-ended - an open-ended venture with quite uncertain outcome, but
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	62 with a high dollar cost attached to it. Given the massive effort required and
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	63 PCB layout labor costs, I currently have no active plans to pursue this idea
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	64 beyond hypothetical.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	65
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	66 Commissioning a new custom RF FEM
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	67 =================================
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	68
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	69 Here is a wild thought: what if instead of twisting over backwards trying to
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	70 hammer an existing RF FEM like M034F into our not-quite-fitting PCB design, we
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	71 were to get an entirely new FEM made specially for us, made exactly the way we
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	72 need it? If we were to venture that way, I would ask for a FEM very similar
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	73 conceptually to M034F, but with a few changes:
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	74
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	75 1) Instead of diplexing between DCS and PCS SAW filter inputs with a 50/50
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	76 energy split, implement another switch (just like the GSM850 Rx switch) for
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	77 PCS Rx, exactly the same way how it is done in classic triband designs like
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	78 our current OM-based one. This change should eliminate the extra 3 dB
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	79 penalty which I assume (for lack of experimental data) must happen with the
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	80 existing M034 FEM. Or as an alternative to making this change, if someone
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	81 who is more knowledgeable than me in this area can explain to me why it isn't
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	82 necessary, I would accept that option as well.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	83
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	84 2) I would ask for a rearranged pinout: the existing M034F pinout does not fit
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	85 at all into our OM-based PCB layout, but it would fit much better with some
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	86 rearrangement.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	87
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	88 3) The hypothetical M034-like FEM would fit into our OM-based PCB layout a lot
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	89 better if it were made a little smaller than the 8.2x5.5 mm size of M034F.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	90 Considering that the original M034F was created some 15-16 y ago, I assume
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	91 that it should be possible to make a smaller version in 2020 or 2021 or
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	92 whenever.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	93
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	94 Timeline sequentiality
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	95 ======================
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	96
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	97 All of the above ideas will be considered on a less hypothetical level after we
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	98 get our already-committed FCM40 product built. FCM40 will be a modem module in
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	99 the same 56.5x36 mm form factor as Huawei GTM900 (with a mostly-compatible FPC
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	100 interface with only a few changes), featuring the same OM-based triband modem
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	101 core as FCDEV3B V2. The reason for this sequencing is that our current FCDEV3B
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	102 suffers from a couple of issues which FCM40 is expected to solve:
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	103
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	104 1) FCDEV3B has a very tight PCB layout: not only do we have the tightly laid out
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	105 core from GTA02, but also the whole board is quite small for the implemented
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	106 peripheral complexity, imposing further constraints from all sides. This
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	107 tight and complex layout makes a poor choice of starting point for bold
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	108 experiments like RFFE changes.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	109
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	110 2) FCDEV3B is locked into Altium. Layout data migration from Altium to FOSS
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	111 appears to be much less feasible than migration from PADS to FOSS, thus
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	112 freeing our PCB layout from the clutches of proprietary software will most
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	113 likely require giving up (or rather setting aside) all of FCDEV3B new layout
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	114 and going back to the GTA02 starting point, which is in PADS format rather
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	115 than Altium. Redoing all of FCDEV3B anew does not sound appealing at all,
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	116 but the much simpler FCM40 board offers a perfect opportunity for a fresh
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	117 start.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	118
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	119 FCM40 will have exactly the same OM-based triband RFFE as our current FCDEV3B,
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	120 but it will be a much simpler board, and if we can get it done in FOSS instead
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	121 of continuing the Altium track, then we would have a very solid reference and a
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	122 good starting point for potential RFFE change experiments.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	123
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	124 Firmware compatibility
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	125 ======================
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	126
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	127 Our current FreeCalypso firmwares drive TSPACT RFFE control signals as follows
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	128 on FC hw family targets (CONFIG_TARGET_FCFAM):
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	129
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	130 TSPACT1 = Rx PCS band
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	131 TSPACT2 = Tx high bands
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	132 TSPACT4 = Tx low bands
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	133 TSPACT5 = Rx GSM850 band
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	134
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	135 The driving of TSPACT1, TSPACT2 and TSPACT4 matches the way these signals have
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	136 been assigned by Openmoko and thus the way they function on our current OM-based
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	137 triband RFFE, whereas TSPACT5 is a new signal which is not wired anywhere on
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	138 our current FCDEV3B. This signal driving arrangement is expected to be
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	139 compatible with all 3 RFFE hw possibilities under consideration:
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	140
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	141 * On our current OM-based triband RFFE it works as is.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	142
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	143 * If we use Epcos M034 or a semi-clone thereof that has the two Tx switches and
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	144 a GSM850 Rx switch but no PCS Rx switch, then we will need to connect TSPACT2,
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	145 TSPACT4 and TSPACT5 per the table above, and leave TSPACT1 unconnected.
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	146
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	147 * If we get a new M034-like FEM custom-made with a full set of all 4 switches,
3fa4006696d0 Quadband-ideas article written Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	148 then all 4 TSPACT signals will need to be connected per the table above.

FreeCalypso > hg > freecalypso-docs

annotate Quadband-ideas @ 23:14391ad53281