CP/PC364 Data Communications & Networks Laboratory

Voltage Controlled Oscillators

PRELAB

Datasheet: XR2207 [Copyright 1975 EXAR Corporation. Datasheet June 1997]

Using the XR-2207 datasheet determine the following and record in your lab notebook:

1. Find and sketch the test circuit for fixed frequency single supply operation.

   Use the information in Table 1, Table 2 and the datasheet to determine the values for the rest of the prelab.

   Table 1: Values for lab 1

   RL	4.7kΩ
   CB	Refer to page 7 of the datasheet
   Ct	Refer to page 7 of the datasheet
   R3	Refer to Figure 8 of datasheet

   Table 2: Available Parts

   Power Supplies	Resistors (Ω)		Capacitors (μF)
   GND (0V)	10	1k	0.001	0.01
   +5V	3.9k	4.7k	0.033	0.047
   +12V	5.1k	10k	0.1	0.22
   -12V	20k	51k	0.33	0.47
   	100k	1M	1	10

2. Using the datasheet, select a resistor value in the mid range, then choose four different capacitor values from the list and determine the frequencies using equation 1.
3. Using the datasheet, select a capacitor value in the mid range, then choose four different resistor values from the list and determine the frequencies using equation 1.

   Equation 1: Frequency

4. Binary Keying Inputs
   • look up the information for binary keying inputs on the datasheet
   • what voltage levels are required for the keying inputs?
   • what hardware will you use for your keying inputs?
   • select a capacitor value, a resistor value to use for R₁ and R₂, and a different resistor value for R₃ and R₄.
   • draw your circuit
5. Determine the frequency of the output waveform for each of the four binary keying input combinations from Table 1 in the datasheet.
   • Copy Table 1 (from the datasheet) into your lab book and calculate and record the frequencies using the equations below.
   Frequency equations:
6. Write down all the parts you will need (chips, resistors, capacitors, # of alligator clips, # of scope probes)