Biomedical Engineering Reference
In-Depth Information
Fig. 5.11 Layout of the
reconfigurable square wave
generator
Programmable
Oscillator
To buffers
Programmable
Resistor
(R
set
)
I
2
C Communication with
micro controller
Table 5.1 Main components of the IR-UWB pulse generator
Functional block
Component
Manufacturer
Square wave oscillator
LTC6905
Linear technology [
10
]
Programmable resistor
AD5286
Analog devices [
11
]
Buffer
NC7WZ126
Fairchild semiconductor [
12
]
XOR gate
NC7SZ86
Fairchild semiconductor [
12
]
resistance value of the oscillator calibration input. It is possible to change the
resistance of this programmable resistor through Inter-Integrated Circuit (I
2
C)
communication with a micro-controller, enabling reconfigurations of the PRF
without intervening with the circuitry. Circuit diagram for this configuration is
shown in Fig.
5.11
. Set of components used in the implementation of the pulse
generator is shown in Table
5.1
.
Circuit components for buffers and XOR gate are chosen considering their fast
transition times and small form factors. Two transmission line sections between
square wave oscillator and buffers, and between buffers and XOR gate are designed
such that the delay introduced by the signal propagation through each path is
