IXZ-500 Dual-Axis Gyroscope

Product Specification

PS-IXZ-0500B-00-03

Release Date: 06/04/09

CONFIDENTIAL & PROPRIETARY

6 of 26

5. Functional Block Diagram

Figure 1

6. Functional Description

6.1

Overview

The IXZ-500 gyroscope consists of two independent vibratory MEMS gyroscopes. One detects rotation about

the X-axis; the other detects rotation about the Z-Axis.

The gyroscope’s proof-masses are electrostatically oscillated at resonance. An internal automatic gain

control circuit precisely controls the oscillation of the proof masses. When the sensor is rotated about the X-

or Z-Axis, the Coriolis Effect causes a vibration that can be detected by a capacitive pickoff. The resulting

signal is amplified, demodulated, and filtered to produce an analog voltage that is proportional to the angular

rate.

6.2

Rate Sensors

The mechanical structures for detecting angular rate about the X- and Z-axes are fabricated using

InvenSense’s proprietary bulk silicon technology. The structures are covered and hermetically sealed at the

wafer level. The cover shields the gyro from electromagnetic and radio frequency interferences (EMI/RFI).

The dual-mass design inherently rejects any signal caused by linear acceleration. The X-gyro and the Z-gyro

have different resonant frequencies to prevent undesired coupling.

6.3

Oscillator Circuit

The oscillator circuit generates electrostatic forces to vibrate the structure at resonance. The circuit detects

the vibration by measuring the capacitance between the oscillating structure and a fixed electrode. The

oscillator circuit switches in quadrature phase with the capacitance measurement in order to vibrate at

resonance.

XAGC 6

ZAGC 15

AZ

24

X4.5OUT

7

14

20

16

IXZ-500

Memory

Trim

Demodulator

Oscillator

Demodulator

Oscillator

Coriolis

Sense

Output Gain

Output Gain

Z-Rate

Sensor

X-Rate

Sensor

1

Coriolis

Sense

Z4.5OUT

Charge Pump

CPOUT

12

5

Z-OUT

Z4.5IN

X4.5IN

X-OUT

Gain

Low-Pass

Filter

+

Gain

Low-Pass

Filter

+

Auto Zero

Auto Zero

Optional

External

Filters

Optional

External

Filters

Optional

PTAT

Sensor

23

VREF

Reference

22

Optional