The invention provides a harmonic direct conversion mixer having a multiplier circuit comprising first and second mixers and a generator for generating two first and two second control signals for controlling the first and second mixers. The control signals are balanced signals and are provided in four phases shifted by π/2 in phase. The frequency of the control signals is different from the frequency of the mixer input signal.
1. A harmonic mixer comprising:
a multiplier circuit comprising first and second mixers; and
a generator for generating two first and two second control signals for controlling said first and second mixers,
wherein said two first and two second control signals are balanced signals and are provided in four phases each shifted by π/2 in phase, and
said control signals having a frequency different from a frequency of a mixer input signal.
2. The harmonic mixer of claim 1 , wherein said multiplier circuit is a Gilbert cell having a plurality of transistors, where all said transistors are used as switches.
3. The harmonic mixer of claim 1 , wherein said generator comprises a voltage controlled oscillator.
4. The harmonic mixer of claim 1 , wherein the frequency of said control signals is half the frequency of the mixer input signal.
5. The harmonic mixer of claim 1 , wherein said first mixer has a pair of field effect transistors and said second mixer has two pairs of field effect transistors.
6. A harmonic direct conversion mixer for I/Q quadrature phase modulation, comprising:
a first multiplier circuit comprising first and second mixers for generating inphase (I) components;
a second multiplier circuit comprising third and fourth mixers for generating quadrature (Q) components; and
a generator for generating two first and two second control signals for controlling said first and second mixer and two third and two fourth control signals for controlling said third and fourth mixer,
wherein said two first, two second, two third and two fourth control signals are balanced signals,
a phase shift of π/2 between said two first and two second control signals is provided,
a phase shift of π/2 between said two third and two fourth control signals is provided,
a phase shift of π/4 between said two first and two second control signals and said two third and two fourth control signals is provided, and
said control signals having a frequency different from a frequency of a mixer input signal.
7. The harmonic mixer of claim 6 , wherein said first and second multiplier circuits each comprise a Gilbert cell having a plurality of transistors, where all said transistors are used as switches.
8. The harmonic mixer of claim 6 , wherein said generator comprises a voltage controlled oscillator and a filter bank.
9. The harmonic mixer of claim 6 , wherein the frequency of said control signals is half the frequency of the mixer input signal.
10. The harmonic mixer of claim 6 , wherein said first and third mixers each comprise a pair of field effect transistors and said second and fourth mixers each comprise two pairs of field effect transistors.
11. The harmonic mixer of claim 8 , wherein said filter bank comprises:
an initial π/4 phase shifter; and
first and second polyphase filters for generating said eight control signals.
12. The harmonic mixer of claim 11 , wherein said π/4 phase shifter has first and second all-pass filters providing first and second differential signals shifted by π/4.