Patent ID: 8659363

Claim:
A quadrature oscillator, comprising: a first filter, comprising: a first capacitor coupled to a first node, wherein the first node is a common node that is either a circuit ground node, a voltage reference node, or a power supply node; a first operational transconductance amplifier (OTA), comprising: an inverting input; a non-inverting input coupled to the first capacitor; a first inverting output; a second inverting output; a third inverting output coupled to the first capacitor; and a non-inverting output; and a second OTA, comprising: a non-inverting input coupled to the first node; an inverting input coupled to the inverting input of the first OTA; and a non-inverting output coupled to the inverting input of the first OTA; and a second filter, comprising: a second capacitor coupled to the first node; a third OTA, comprising: an inverting input coupled to the first inverting output of the first OTA; a non-inverting input coupled to the second inverting output of the first OTA and the second capacitor; a first non-inverting output coupled to the inverting input of the first OTA; a second non-inverting output coupled to the non-inverting input of the first OTA; a first inverting output coupled to the second capacitor; and a second inverting output; and a fourth OTA, comprising: a non-inverting input coupled to the first node; an inverting input coupled to the inverting input of the third OTA; and a non-inverting output coupled to the inverting input of the third OTA; wherein the first OTA, the second OTA, the third OTA, and the fourth OTA have substantially the same transconductance, and the first capacitor and the second capacitor have substantially the same capacitance value.