He actually told me that it is not a process issue even though
he did mention that things like EMC/EMI get tricky when going to
fine process like 0.25um or lower with lower Vdd and lower=20
latch-up threshold voltage. He specifically said that it is
an architecture issue and they would have to come out
something like PIC20 to incorporate this. Of course this
is not a highly sought features in the low end so they
will not come out a PIC20 architecture just to make faster
ADC possible. However I still do not quite understand this.

We have also requested that the resolution in the comparator=20
voltage reference unit should get better ( better than the
32 steps high range /24 steps low range right now).

By the way, there are faster ADCs (500ksps) in the dsPIC side.

For high resolution, take a look at Silabs C8051F064. They
even have a US$29 demo kit with built in USB interface
to program the chip.

Regards,
Xiaofan

-------------------------------------------------
Key features for the C8051F064:

Analog Peripherals
- Two 16-Bit SAR ADCs
* 16-bit resolution
* =B10.75 LSB INL, guaranteed no missing codes
* Programmable throughput up to 1 Msps
* Operate as two single-ended or one differential converter
* Direct memory access; data stored in RAM without
software overhead
* Data-dependent windowed interrupt generator
- 10-bit SAR ADC (C8051F060/1/2/3)
* Programmable throughput up to 200 ksps
* 8 external inputs, single-ended or differential
* Built-in temperature sensor
- Two 12-bit DACs (C8051F060/1/2/3)
* Can synchronize outputs to timers for jitter-free waveform
generation
- Three Analog Comparators
* Programmable hysteresis/response time
- Voltage Reference
- Precision VDD Monitor/Brown-Out Detector
High Speed 8051 =B5C Core
- Pipelined instruction architecture; executes 70% of
instruction set in 1 or 2 system clocks
- Up to 25 MIPS throughput with 25 MHz clock
- Flexible Interrupt sources
Memory
- 4352 Bytes internal data RAM (4 k + 256)
- 64 kB (C8051F060/1/2/3/4/5), 32 kB (C8051F066/7)
Flash; In-system programmable in 512-byte sectors
- External 64 kB data memory interface with multiplexed
and non-multiplexed modes (C8051F060/2/
4/6)

Clock Sources
- Internal calibrated precision oscillator: 24.5 MHz
- External oscillator: Crystal, RC, C, or clock
Supply Voltage .......................... 2.7 to 3.6 V



-----Original Message-----
From: Michael Rigby-Jones=20
Sent: Monday, August 01, 2005 5:51 PM
...
>I could understand that why Microchip can not put a MCU into
>a 3mmx3mm small package like C8051F30x (bigger die than 8051=20
>and process related issues) but I am not so sure why Microchip can=20
>not put a fast ADC (10 bit and >=3D 200ksps). What could be=20
>the problem?
>

Much more likely a process issue, I'd have thought.  The current=20
ADC works on a switched capacitor scheme rather than the=20
traditional R2R ladder.  Presumably this is because it provides=20
the best accuracy/lowest costs for the process that Microchip=20
use, which gives a slower conversion rate but which is p
erfectly adequate for probably 99% of the applications a=20
PIC would be used in.  Personaly I'd far rather they=20
improved the resolution to 12bits on the higher end 18F=20
rather than up the sample rate.

Regards

Mike

--=20
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