Poly-phase filter with phase tuning
A poly-phase filter receives inphase input signals I and Ī and quadrature input signals Q and Q , and provides inphase output signals I out and I out and quadrature output signals Q out and Q out . The capacitance of each variable capacitor connected to the terminals providing inphase output signals I out and I out is and the capacitance of each variable capacitor connected to the terminals providing quadrature output signals Q out and Q out , are different in value, and preferably by twice a predetermined value. This is because adjustment to the capacitance values may be made to each set of variable capacitors by the predetermined value.
1. A poly-phase filter, comprising:
terminals for receiving inphase input signals I and Ī, and quadrature input signals Q and Q ;
terminals for providing inphase output signals I out and I out , and quadrature output signals Q out and Q out ,
variable resistors connecting across the terminals for receiving inphase input signal I, quadrature input signal Q, inphase input signal Ī, and quadrature input signal Q , and the terminals for providing inphase output signal I out , quadrature output signal Q out , inphase output signal I out , and quadrature output signal Q out , respectively; and
variable capacitors connecting across the terminals for receiving inphase input signal I, quadrature input signal Q, inphase input signal Ī, and quadrature input signal Q , and the terminals for providing quadrature output signal Q out , inphase output signal I out , quadrature output signal Q out , and inphase output signal I out , respectively, wherein each adjustment that increases or decreases the capacitance of each variable capacitor connected to the terminals providing inphase output signals I out , and I out correspondingly decreases or increases by an equal amount the capacitance of each variable capacitor connected to the terminals providing quadrature output signals Q out and Q out .
2. The poly-phase filter of claim 1 , wherein the capacitance of each variable capacitor connected to the terminals providing inphase output signals I out and I out differs from the capacitance of each variable capacitor connected to the terminals providing quadrature output signals Q out and Q out by twice a predetermined amount.
3. The poly-phase filter of claim 1 , wherein the resistance of each variable resistor connected to the terminals providing inphase output signals I out and I out and the resistance of each variable resistor connected to the terminals providing quadrature output signals Q out and Q out are different in value.
4. A poly-phase filter, comprising:
terminals for receiving inphase input signals I and Ī, and quadrature input signals Q and Q ;
terminals for providing inphase output signals I out and I out , and quadrature output signals Q out and Q out ,
variable resistors connecting across the terminals for receiving inphase input signal I, quadrature input signal Q, inphase input signal Ī, and quadrature input signal Q , and the terminals for providing inphase output signal I out , quadrature output signal Q out , inphase output signal I out , and quadrature output signal Q out , respectively, wherein each adjustment increases or decreases the resistance of each variable resistor connected to the terminals providing inphase output signals I out and I out correspondingly decreases or increases by an equal amount the resistance of each variable resistor connected to the terminals providing quadrature output signals Q out and Q out , are different in value; and
variable capacitors connecting across the terminals for receiving for receiving inphase input signal I, quadrature input signal Q, inphase input signal Ī, and quadrature input signal Q , and the terminals for providing quadrature output signal Q out , inphase output signal I out , quadrature output signal Q out , and inphase output signal I out , respectively.
5. The poly-phase filter of claim 4 , wherein the resistance of each variable resistor connected to the terminals providing inphase output signals I out and I out and the resistance of each variable resistor connected to the terminals providing quadrature output signals Q out and Q out , differs in value by twice a predetermined amount.