FULLY DIFFERENTIAL QUADRATURE DRIVER
According to an embodiment, a circuit for quadrate error correction is proposed. The circuit includes a set of first resistors receiving a demodulated low-voltage differential signal from gyroscope sense electrodes; an ICMFB circuit with adjustable current sinks maintaining a low-voltage input level by controlling current; an HV driver circuit creating a high-voltage differential output from the low-voltage input, supplied to gyroscope correction electrodes; a set of second resistors where the input-to-output differential gain is defined by their relative resistances; and an output common-mode feedback circuit adapting the high-voltage output to a low-voltage for the HV driver.
1 . A circuit for correcting a quadrature error in a gyroscope, the circuit comprising:
a pair of first resistors configured to receive a differential input low-voltage signal, a differential value of the differential input low-voltage signal set based on a demodulated quadrature signal measured by sense electrodes of the gyroscope;
an input common-mode feedback (ICMFB) circuit coupled to the pair of first resistors, the ICMFB circuit comprising a pair of adjustable current sinks configured to regulate an input common-mode of the circuit at a low-voltage level by managing current flowing through the adjustable current sinks;
a high-voltage (HV) driver circuit configured to provide a differential output high-voltage signal based on the differential input low-voltage signal, the differential output high-voltage signal being fed to quadrature correction electrodes of the gyroscope to correct the quadrature error;
a pair of second resistors, wherein a differential gain between the input differential input low-voltage signal and the differential output high-voltage signal is determined by a relative resistance values of the pair of first resistors and pair of second resistors; and
an output common-mode feedback circuit configured to convert a high-voltage common-mode output of the circuit to a low-voltage level suitable for the HV driver circuit.
2 . The circuit of claim 1 , wherein the ICMFB circuit further comprises:
a differential amplifier having a first input coupled to a reference voltage, the differential amplifier configured to provide a control signal based on the reference voltage to each of the adjustable current sinks to manage current flowing through the adjustable current sinks; and
an adder circuit configured to combine a non-inverting and an inverting signal of the differential input low-voltage signal, an output of the adder circuit coupled to a second input of the differential amplifier.
3 . The circuit of claim 1 , wherein the OCMFB circuit comprises a pair of third resistors and a fourth resistor forming a resistor divider, wherein the resistor divider is configured to attenuate the high-voltage level at the output of the HV driver circuit to the low-voltage level suitable for the HV driver circuit.
4 . The circuit of claim 3 , wherein the OCMFB circuit further comprises a differential amplifier having a first input terminal coupled to a shared node between the third resistors and the fourth resistor, a second input terminal of the differential amplifier coupled to a reference voltage, the differential amplifier configured to provide a low-voltage signal to the HV driver circuit based on a difference between a output common-mode voltage of the circuit and the reference voltage.
5 . The circuit of claim 1 , wherein the HV driver circuit comprises a folded cascode operational amplifier with a class A output stage and a common-mode feedback circuit.
6 . The circuit of claim 1 , wherein the HV driver circuit comprises a first low-voltage stage, a second low-voltage stage, and a third high-voltage stage.
7 . The circuit of claim 6 , wherein the HV driver circuit further comprises a class A output stage.
8 . A system for correcting a quadrature error in a gyroscope, the system comprising:
a digital control circuit configured to generate a differential input low-voltage signal based on a demodulated quadrature signal from sense electrodes of the gyroscope; and
a low-voltage to high-voltage (LV-to-HV) differential translator circuit, the LV-to-HV differential translator circuit comprising:
a pair of first resistors configured to receive the differential input low-voltage signal,
an input common-mode feedback (ICMFB) circuit coupled to the pair of first resistors, the ICMFB circuit comprising a pair of adjustable current sinks configured to regulate an input common-mode of the LV-to-HV differential translator circuit at a low-voltage level by managing current flowing through the adjustable current sinks,
a high-voltage (HV) driver circuit configured to provide a differential output high-voltage signal based on the differential input low-voltage signal, the differential output high-voltage signal being fed to quadrature correction electrodes of the gyroscope to correct the quadrature error,
a pair of second resistors, wherein a differential gain between the input differential input low-voltage signal and the differential output high-voltage signal is determined by a relative resistance values of the pair of first resistors and pair of second resistors, and
an output common-mode feedback circuit configured to convert a high-voltage common-mode output of the LV-to-HV differential translator circuit to a low-voltage level suitable for the HV driver circuit.
9 . The system of claim 8 , further comprising the gyroscope.
10 . The system of claim 8 , wherein the ICMFB circuit further comprises:
a differential amplifier having a first input coupled to a reference voltage, the differential amplifier configured to provide a control signal based on the reference voltage to each of the adjustable current sinks to manage current flowing through the adjustable current sinks; and
an adder circuit configured to combine a non-inverting and an inverting signal of the differential input low-voltage signal, an output of the adder circuit coupled to a second input of the differential amplifier.
11 . The system of claim 8 , wherein the OCMFB circuit comprises a pair of third resistors and a fourth resistor forming a resistor divider, wherein the resistor divider is configured to attenuate the high-voltage level at the output of the HV driver circuit to the low-voltage level suitable for the HV driver circuit.
12 . The system of claim 11 , wherein the OCMFB further comprises a differential amplifier having a first input terminal coupled to a shared node between the third resistors and the fourth resistor, a second input terminal of the differential amplifier coupled to a reference voltage, the differential amplifier configured to provide a low-voltage signal to the HV driver circuit based on a difference between a output common-mode voltage of the circuit and the reference voltage.
13 . The system of claim 8 , wherein the HV driver circuit comprises a folded cascode operational amplifier with a class A output stage and a common-mode feedback circuit.
14 . The system of claim 8 , wherein the HV driver circuit comprises a first low-voltage stage, a second low-voltage stage, and a third high-voltage stage.
15 . A system to correct a quadrature error in a gyroscope, the system comprising:
a digital control circuit configured to generate a differential input low-voltage signal based on a demodulated quadrature signal from sense electrodes of the gyroscope; and
a low-voltage to high-voltage (LV-to-HV) differential translator circuit configured to receive the differential input low-voltage signal and generate a differential output low-voltage signal for quadrature correction electrodes of the gyroscope to correct the quadrature error, the LV-to-HV differential translator circuit comprising:
an input common-mode feedback (ICMFB) circuit configured to regulate an input common-mode of the LV-to-HV differential translator circuit at a low-voltage level,
a high-voltage (HV) driver circuit configured to provide the differential output high-voltage signal based on the differential input low-voltage signal, and
an output common-mode feedback circuit configured to convert a high-voltage common-mode output of the LV-to-HV differential translator circuit to a low-voltage level suitable for the HV driver circuit.
16 . The system of claim 15 , wherein the ICMFB circuit comprises:
a pair of adjustable current sinks;
a differential amplifier having a first input coupled to a reference voltage, the differential amplifier configured to provide a control signal based on the reference voltage to each of the adjustable current sinks to manage current flowing through the adjustable current sinks; and
an adder circuit configured to combine a non-inverting and an inverting signal of the differential input low-voltage signal, an output of the adder circuit coupled to a second input of the differential amplifier.
17 . The system of claim 15 , wherein the OCMFB circuit comprises a pair of third resistors and a fourth resistor forming a resistor divider, wherein the resistor divider is configured to attenuate the high-voltage level at the output of the HV driver circuit to the low-voltage level suitable for the HV driver circuit.
18 . The system of claim 17 , wherein the OCMFB further comprises a differential amplifier having a first input terminal coupled to a shared node between the third resistors and the fourth resistor, a second input terminal of the differential amplifier coupled to a reference voltage, the differential amplifier configured to provide a low-voltage signal to the HV driver circuit based on a difference between a output common-mode voltage of the circuit and the reference voltage.
19 . The system of claim 15 , wherein the HV driver circuit comprises a folded cascode operational amplifier with a class A output stage and a common-mode feedback circuit.
20 . The system of claim 15 , wherein the HV driver circuit comprises a first low-voltage stage, a second low-voltage stage, and a third high-voltage stage.