US 2003/0114129 A1 · System and method for a radio frequency receiver front end utilizing a balun to couple a low-noise amplifier to a mixer

Abstract

An embodiment of this invention pertains to a fully integrated, highly linear, and power-efficient balun circuit and voltage-to-current converter that interfaces a single-ended low noise amplifier (“LNA”) and a differential mixer. The balun circuit includes components that perform the following functions: provide a load element for the LNA, resonate at the desired frequency of operation to maximize a gain of a single-ended signal output from the single-ended LNA, stabilize the gain of the single-ended signal; convert the single-ended signal to a differential signal, match the impedance between the single-ended LNA and the differential mixer to maximize the power transfer of the differential signal, improve the balance of the differential signal, provide a bias to the LNA, provide a bias for a voltage-to-current converter portion of the differential mixer, and differentially drive a pair of grounded source transistors that linearly convert the differential signal in voltage form to current form. The voltage to current conversion occurs without using a current source in the voltage-to-current converter portion of the differential mixer.

Claims35

Dependent claims

An integrated radio frequency (“RF”) receiver front end, comprising:

a balun circuit, comprising:
a first inductor;
a second inductor, magnetically coupled to the first inductor, to transform a single-ended signal to a differential signal, wherein the second inductor has a center tap node;
a first capacitor, coupled in parallel to the first inductor, to form a resonance with the first inductor to maximize a gain of the single-ended signal;
a first resistor, coupled in parallel to the first capacitor, to stabilize the gain of the single-ended signal;
a second capacitor, coupled at one end to the center tap node and to AC ground at the other end, to improve the balance between a first half of the differential signal and a second half of the differential signal;
a third capacitor, coupled in parallel to the second inductor;
a fourth capacitor, coupled in parallel to the third capacitor, that together with the third capacitor matches the impedance between a low noise amplifier and a mixer;
and
the mixer, coupled to the balun circuit, comprising:
a first transistor having a source, a gate, and a drain, the gate coupled to the fourth capacitor, the source coupled to ground, and the drain producing a first half of a differential signal in current form;
and
a second transistor, together with the first transistor, to convert the differential signal from a voltage form to a current form, the second transistor having a source, a gate, and a drain, the gate coupled to the fourth capacitor, the source coupled to ground, and the drain producing a second half of the differential signal in current form.

10 more elements

Dependencies are inferred from the claim text.

System and method for a radio frequency receiver front end utilizing a balun to couple a low-noise amplifier to a mixer

Life of this patent

System and method for a radio frequency receiver front end utilizing a balun to couple a low-noise amplifier to a mixer

Life of this patent

Abstract

Claims35