Continuous time analogue/digital converter
Continuous time analog/digital converter, comprising a sigma delta modulator (MSD 1 ) configured to receive an analog input signal (x(t)) and comprising high-pass filtering means (MF) the chopping frequency of which is equal to half of the sampling frequency (Fs) of the quantization means (QTZ) of the modulator (MSD 1 ).
1. A sigma delta modulator comprising:
a first summer configured to add an analogue input signal to a feedback signal to generate a modified analogue signal;
a high-pass filter configured to filter the modified analogue signal to generate a filtered modified analogue signal; and
a quantizer configured to sample the filtered modified analogue signal to generate a digital signal, the high-pass filter comprising an amplifier coupled between an output of the quantizer and an input of the first summer.
2. The sigma delta modulator of claim 1 further comprising a digital to analogue converter configured to convert the digital signal to generate the feedback signal.
3. The sigma delta modulator of claim 1 , wherein the high-pass filter has a chopping frequency, and wherein the quantizer has sampling frequency, the chopping frequency being half of the sampling frequency.
4. The sigma delta modulator of claim 3 , wherein the sampling frequency is 4 GHz and the chopping frequency is 2 GHz.
5. The sigma delta modulator of claim 1 , wherein the high-pass filter further comprises a first resonator.
6. The sigma delta modulator of claim 5 , wherein the high-pass filter further comprises a second resonator.
7. The sigma delta modulator of claim 1 further comprising a delay component coupled between an output of the quantizer and an input of the first summer.
8. A wireless communication device comprising:
a sigma delta modulator configured to receive an analogue input signal, the sigma delta modulator comprising:
a high-pass filter configured to filter the analogue input signal to generate a filtered analogue signal; and
a quantizer configured to sample the filtered analogue signal to generate a digital signal;
a low noise amplifier comprising an input coupled to an antenna and an output coupled to the sigma delta modulator; and
a digital signal processor configured to receive the digital signal from the sigma delta modulator.
9. The wireless communication device of claim 8 , wherein the high-pass filter has a chopping frequency, and wherein the quantizer has sampling frequency, the chopping frequency being less than the sampling frequency.
10. The wireless communication device of claim 9 , wherein the chopping frequency is equal to half of the sampling frequency.
11. The wireless communication device of claim 8 further comprising:
at least one summer configured to add the analogue input signal to a feedback signal; and
a digital to analogue converter configured to convert the digital signal to generate the feedback signal.
12. The wireless communication device of claim 11 further comprising a delay component coupled between an output of the quantizer and an input of the at least one summer.
13. The wireless communication device of claim 8 , wherein the high-pass filter comprises at least one resonator and at least one variable-gain amplifier.
14. The wireless communication device of claim 8 , wherein the quantizer has a sampling frequency, the sampling frequency being equal to twice the frequency of the analogue input signal.
15. A continuous time analogue/digital converter comprising:
a sigma delta modulator configured to receive an analogue input signal, the sigma delta modulator comprising:
a quantizer having a sampling frequency; and
a high-pass filter having a chopping frequency, the chopping frequency being less than the sampling frequency.
16. The continuous time analogue/digital converter of claim 15 , wherein the sigma delta modulator further comprises at least one summer, and wherein the high-pass filter comprises at least one unit including a resonator and a variable-gain amplifier coupled between an output of the quantizer and an input of the at least one summer, the variable-gain amplifier having a gain set at a value wherein a resonance frequency of the resonator is equal to the chopping frequency.
17. The continuous time analogue/digital converter of claim 16 , wherein the high-pass filter comprises at least one other unit.
18. The continuous time analogue/digital converter of claim 16 , wherein the sigma delta modulator further comprises a delay component coupled between the output of the quantizer and the input of the variable-gain amplifier, the delay component being configured to delay a digital output signal of the quantizer by a period equal to half of the sampling period of the quantizer.
19. The continuous time analogue/digital converter of claim 15 , wherein the chopping frequency is equal to half of the sampling frequency.
20. The continuous time analogue/digital converter of claim 15 , wherein the sigma delta modulator further comprises:
at least one summer having a first input coupled to the analogue input signal and an output coupled to the input of the high-pass filter, an output of the high-pass filter coupled to an input of the quantizer; and
a digital to analogue converter having an input coupled to an output of the quantizer and an output of the digital to analogue converter being coupled to a second input of the at least one summer.