MODELING OF ANALOG BLOCKS IN VERILOG-A
233
Quadrature oscillator
This oscillator is used in quadrature receiver design. A phase shifter is
ordinarily used to generate the quadrature signal from one signal source.
However, it is difficult to implement a phase shifter into a wide band model.
A quadrature signal consists of two signals with a 90° phase difference but
with identical noise and amplitude.
Phase shifter
In digital RF system designs the quadrature signal processing involves
the phase splitting of high-frequency signals. The most common use of such
components is to generate two signals that have a 90° phase difference based
on one signal source.
Most of the itemized models are provided in two different versions for
passband and baseband signal handling. In this second part of the section
the baseband principle and the equivalent baseband models are briefly
introduced.
The complex baseband simulation is a commonly used technique in
system level simulation. The principle of complex baseband simulation is
presented in Section 4.3. Starting with the release IC 4.4.6 Cadence also
provides analog behavioral models for complex baseband signals.
As shown in Figure 10-11 each input and output signal of a baseband
model has two components (pins) in contrast to a passband model. They
represent a complex valued signal. It can be interpreted as amplitude and
phase of a modulated carrier transformed from polar to rectangular
coordinates. The inphase component is represented by the signal I and the
quadrature component is represented by the signal Q. The transformation of
a passband signal to its equivalent baseband representation is also described
in Section 4.3.
Figure 10-11. Equivalent baseband model
Summary :
A phase shifter is ordinarily used to generate the quadrature signal from one signal source. A quadrature signal consists of two signals with a 90° phase difference but with identical noise and amplitude. Phase shifter In digital RF system designs the quadrature signal processing involves the phase splitting of high-frequency signals.
Tags :
baseband,phase,quadrature,signals,model,complex,two,section,passband,simulation,shifter,models,used