| US 7,577,418 B2 | ||
| Sub-harmonic mixer and down converter with the same | ||
| Jen-Chung Chang, Taoyuar County (Taiwan); Chia-Jung Hsu, Hsinchu (Taiwan); Shey-Shi Lu, Taipei (Taiwan); Hsiao-Chin Chen, Hsinchu (Taiwan); and Tzu-Chao Lin, Kaohsiung (Taiwan) | ||
| Assigned to United Microelectronics Corp., Hsinchu (Taiwan); and National Taiwan University, Taipei (Taiwan) | ||
| Filed on Jul. 18, 2006, as Appl. No. 11/458,190. | ||
| Prior Publication US 2008/0032659 A1, Feb. 07, 2008 | ||
| Int. Cl. H04B 1/26 (2006.01) | ||
| U.S. Cl. 455—323 [455/324; 455/326; 327/102; 327/359; 327/119] | 17 Claims |
| 1. A sub-harmonic mixer, used for mixing a poly-phase local oscillation (LO) signal and a radio frequency (RF) signal to produce
a base band signal, the sub-harmonic mixer comprising:
a differential amplifying unit, amplifying the RF signal;
a current buffer unit, coupled to the differential amplifying unit for gaining the output signal of the differential amplifying
unit; and
a switching unit, coupled to the current buffer unit, switching the output signal of the current buffer unit to the base band
signal based on the poly-phase LO signal,
wherein the differential amplifying unit comprises:
a first resonance circuit, coupled to an supply voltage for orienting the amplified RF signal to the current buffer unit and
orienting a leakage signal to the supply voltage;
a first resistor, the first terminal of the first resistor being directly coupled to the supply voltage;
a second resistor, the first terminal of the second resistor being directly coupled to the supply voltage;
a first N-type transistor, the drain of the first N-type transistor being coupled to the first resonance circuit, the gate
of the first N-type transistor being coupled to the second terminal of the first resistor, and the source of the first N-type
transistor being coupled to a ground voltage;
a second N-type transistor, the drain of the second N-type transistor being coupled to the first resonance circuit, the gate
of the second N-type transistor being coupled to the second terminal of the second resistor, and the source of the second
N-type transistor being coupled to the ground voltage;
a first capacitor, the first terminal of the first capacitor being coupled to the gate of the first N-type transistor;
a second capacitor, the first terminal of the second capacitor being coupled to the gate of the second N-type transistor;
a first inductance, the first terminal of the first inductance being coupled to the second terminal of the first capacitor,
and the second terminal of the first inductance being coupled to the second terminal of the second capacitor;
a third capacitor, the first terminal of the third capacitor being coupled to the first terminal of the first inductance,
and the second terminal of the third capacitor being used for receiving the RF signal; and
a fourth capacitor, the first terminal of the fourth capacitor being coupled to the second terminal of the first inductance,
and the second terminal of the fourth capacitor being used for receiving the RF signal; and
the current buffer unit comprises:
a first P-type transistor, the source of the first P-type transistor being coupled to the drain of the first N-type transistor,
and the gate of the first P-type transistor being coupled to the ground voltage;
a second P-type transistor, the source of the second P-type transistor being coupled to the drain of the second N-type transistor,
and the gate of the second P-type transistor being coupled to the ground voltage; and
a second resonance circuit, connected in series between the drains of first P-type transistor and the ground voltage, and
between the drains of second P-type transistor and the ground voltage, for orienting the output signal of the current buffer
unit to the switching unit and orienting the leakage signal to the ground voltage.
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