2.4-GHz receiver for sensor applications

Efficient current reuse for low-power transceivers

“…The RF front-end presented in [1] was the basis for this design example. The simulated current consumptions of the merged LNA and mixer and LO buffers were approximately 1.4 and 1.1 mA, respectively.…”

“…The LO buffers driving the quadrature mixers are similar to the ones used in [1] except the tail current sources are omitted. Because both the LNA and mixer switch transistors are biased by current mirrors, the dc current through one LO buffer (I LO ) is achieved by subtraction:…”

“…The quadrature downconversion mixers are resistively loaded in this design example. The resistor values were chosen such that the dc level at the output node is compatible with the mixer/baseband interface [1]. Two LO buffers driving quadrature mixers are used as active boosting elements, as is shown in Fig.…”

“…In a merged LNA and mixer topology shown in Fig. 1, the constant boost current I boost is approximately 70% of the dc current of the input stage [1]. A possible way to exploit the PMOS boost source is to use it as an additional transconductance stage [5].…”

“…To achieve sufficient receiver performance, both the low-noise amplifier (LNA) and local oscillator (LO) signal generation circuits require remarkably more current compared to analog baseband (BB). For example, in the design example presented in [1], the current consumption of the RF parts is approximately 90% of the total receiver current consumption. For that reason, power optimization should be concentrated on the blocks and elements operating at the RF.…”