Time-domain multiplexed signal processing block and method for use with multiple MEMS devices
View Patent ↗A sense channel signal processing block is time-domain multiplexed among multiple MEMS devices and utilizes an anti-aliasing filter disposed after track-and-hold switches, to prevent the bandwidth of the sense channel from being limited by the anti-aliasing filter.
1. A sense channel system comprising:
a signal processing module having an input section coupled to an analog output section of each of a plurality of MEMS devices and further having an output section,
wherein the signal processing module processes signals from the analog output section of each of the plurality of MEMS devices in a multiplexed, time domain manner, and
the signal processing module includes a zero-IF mixer configured to demodulate output signals from the plurality of MEMS devices, the zero-IF mixer having a plurality of internal circuit branches associated with the plurality of MEMS devices, respectively.
2. The system of claim 1 wherein the signal processing module, wherein the zero-IF mixer is operatively coupled intermediate a programmable gain amplifier section and a rate amplifier section.
3. The system of claim 1 wherein the signal processing module further comprises:
a plurality of filters, and
a plurality of rate amplifier switches, each having an input section coupled to an output of a rate amplifier and an output section coupled to one of the filters,
wherein each of the plurality of rate amplifier switches and filters is associated with one of the MEMS devices.
4. The system of claim 1 wherein the signal processing module further comprises:
a plurality of trans-impedance amplifiers each having an output section coupled to an input of a programmable gain amplifier,
wherein each of the plurality of trans-impedance amplifiers is associated with one of the MEMS devices.
5. The system of claim 1 wherein each of the plurality of MEMS devices comprises a gyroscope.
6. The system of claim 1 wherein the signal processing module functions as a sense channel for only one of the plurality of MEMS devices at a given time.
7. A sense channel apparatus comprising:
a) a plurality of trans-impedance amplifiers each having an input section for receiving an analog output signal from one of a plurality of MEMS devices and an output section coupled to an input of a programmable gain amplifier;
b) a zero-IF mixer having a plurality of internal circuit branches associated with the plurality of MEMS devices, respectively, operatively coupled intermediate an output of the programmable gain amplifier and an input of a rate amplifier;
c) a plurality of rate amplifier switches, each having an input section coupled to an output of the rate amplifier; and
d) a plurality of filters, each having an input coupled to an output of one of the plurality of rate amplifier switches.
8. The sense channel apparatus of claim 7 in combination with a plurality of MEMS devices, each having an analog-output section coupled to an input section of one of the plurality of trans-impedance amplifiers.
9. The sense channel apparatus of claim 8 wherein at least one of the MEMS devices comprises a gyroscope.
10. A method of multiplexing an output of a plurality of MEMS devices through a single sense channel comprises:
A) providing a signal processing module having an input section coupled to output sections of the plurality of MEMS devices, respectively, and further having an output section, and
B) processing signals from the output sections of the plurality of MEMS devices in a multiplexed, time domain manner,
wherein the signal processing module includes a zero-IF mixer having a plurality of internal circuit branches associated with the plurality of MEMS devices, respectively.
11. The method of claim 10 wherein B) comprises:
B1) processing signals from a first of the plurality of MEMS devices with the signal processing module block during a first time segment.
12. The method of claim 11 wherein B) comprises:
B2) processing signals from a second of the plurality of MEMS devices with the signal processing module during a second time segment different from the first time segment.
13. The sense channel system according to claim 1 , wherein each internal circuit branch outputs a signal indicating operation of associated one of the MEMS devices.
14. The sense channel apparatus according to claim 7 , wherein each internal circuit branch outputs a signal indicating operation of associated one of the MEMS devices.
15. The method according to claim 10 , wherein each internal circuit branch outputs a signal indicating operation of associated one of the MEMS devices.
16. The sense channel system of claim 1 , wherein
the zero-IF mixer includes a demodulator and a plurality of buffers,
each of the plurality of the internal circuit branches has one of the plurality of buffers,
the demodulator is coupled to each of the plurality of buffers, and
each of the plurality of buffers is associated with one of the plurality of MEMS devices.
17. The sense channel apparatus of claim 7 , wherein
the zero-IF mixer includes a demodulator and a plurality of buffers,
each of the plurality of the internal circuit branches has one of the plurality of buffers,
the demodulator is coupled to each of the plurality of buffers, and
each of the plurality of buffers is associated with one of the plurality of MEMS devices.
18. The sense channel apparatus of claim 7 further comprising:
a plurality of trans-impedance amplifier switches, each having an input section coupled to the output section of one of the plurality of trans-impedance amplifiers and an output section coupled to the input section of the programmable gain amplifier,
wherein each of the plurality of trans-impedance amplifier switches operates in synchronization with corresponding one of the plurality of rate amplifier switches.
19. The sense channel system of claim 3 , wherein each of the filters is implemented with a resistor and a capacitor.
20. The sense channel apparatus of claim 7 , wherein each of the filters is implemented with a resistor and a capacitor.