Phase shifter circuit of optical encoder
AssigneePixart Imaging Inc.
InventorsCHUANG-SHEN VOO, Kuan-Choong Shim, Gim-Eng Chew
Life of this patent
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Abstract
There is provided a phase shifter circuit of an optical encoder. The phase shifter circuit receives a first signal, a second signal, a third signal and a fourth signal sequentially having a 90-degree phase shift, and includes a first cascaded resistor string, a second cascaded resistor string, a third cascaded resistor string and a fourth cascaded resistor string. The first, second, third and fourth cascaded resistor strings respectively delay the first, third, second and fourth signals by selecting a switch connected at a tap-out node of the first, second, third and fourth cascaded resistor strings to correct phase deviations between incremental signals and an index signal and/or between incremental signals.
Claims20
A phase shifter circuit of an optical encoder, the phase shifter circuit being configured to receive a first signal, a second signal, a third signal and a fourth signal sequentially having a phase shift, the phase shifter circuit comprising:
- a first resistor string, two ends of the first resistor string configured to receive the first signal and the fourth signal, respectively;
- a second resistor string, two ends of the second resistor string configured to receive the third signal and the second signal, respectively;
- a third resistor string, two ends of the third resistor string configured to receive the second signal and the first signal, respectively;
- a fourth resistor string, two ends of the fourth resistor string configured to receive the fourth signal and the third signal, respectively;
- a first amplifier, having two inputs coupled to the first resistor string and the second resistor string respectively via an input resistor and multiple switching devices;
- a second amplifier, having two inputs coupled to the third resistor string and the fourth resistor string respectively via an input resistor and multiple switching devices;
- and
- four feedback resistors, respectively coupled between one input and one output of the first amplifier and the second amplifier,
- wherein a ratio of one feedback resistor and the input resistor is determined corresponding to a conducting of the multiple switching devices.
A phase shifter circuit of an optical encoder, the phase shifter circuit being configured to receive a first signal, a second signal, a third signal and a fourth signal sequentially having a phase shift, the phase shifter circuit comprising:
- a first resistor string, two ends of the first resistor string configured to receive the first signal and the fourth signal, respectively;
- a second resistor string, two ends of the second resistor string configured to receive the third signal and the second signal, respectively;
- a third resistor string, two ends of the third resistor string configured to receive the second signal and the first signal, respectively;
- a fourth resistor string, two ends of the fourth resistor string configured to receive the fourth signal and the third signal, respectively;
- a first amplifier, having two inputs coupled to the first resistor string and the second resistor string respectively via an input resistor and multiple switching devices or multiple sub-switching devices;
- a second amplifier, having two inputs coupled to the third resistor string and the fourth resistor string respectively via an input resistor and multiple switching devices or multiple sub-switching devices, and
- four feedback resistors, respectively coupled between one input and one output of the first amplifier and the second amplifier,
- wherein a ratio of one feedback resistor and the input resistor is determined corresponding to conducting of the multiple switching devices and the multiple sub-switching devices.
Dependencies are inferred from the claim text.