# Question 12.2: For the circuit shown in Fig. 12.8, it is given that: VYY = ......

For the circuit shown in Fig. 12.8, it is given that:$\ V_{YY}$ = 20 V,$\ V_{Z1}$ = 6.8 V,$\ V_{Z2}$ = 3.8 V,$\ h_{rb} = 3 × 10^{−4}$,$\ h_{ib}$ = 20Ω,$\ h_{ob}$ = 0.5μmhos, α = 0.98 and$\ R_{E}$ = 1kΩ. Find the slope error: (a) when$\ R_{L}$ = ∞ (b) when$\ R_{L}$ = 200 kΩ and (c) when$\ R_{L}$ = 50 kΩ.

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$\ V_{EE} = V_{Z1} + V_{Z2}$ = 6.8 + 3.8 = 10.6 V
$\ V_{CC} = V_{YY} − V_{EE}$ = 20 − 10.6 = 9.4 V

Taking the junction voltages into account, the sweep voltage is:
$\ V_{s} = V_{CC} − V_{BE}$ = 9.4 − 0.6 = 8.8 V.
(a)   The slope error of a transistor constant current sweep is:

$\ e_{s} = \frac{V_{s}}{V_{i}}\left[h_{rb} + \frac{h_{ob}}{α} (R_{E} + h_{ib})\right]$

$\ V_{i} = V_{EE} − V_{γ} = 10.6 − 0.5 = 10.1 V and V_{s}$ = 8.8 V

$\ e_{s} = \frac{8.8}{10.1}\left[3 × 10^{−4} + \frac{0.5 × 10^{−6}}{0.98} (1020)\right]× 100 = \frac{8.8}{10.1} (0.081)$ = 0.07 %

This error is small and hence, the sweep is linear.
(b)   If$\ R_{L}$ is connected as the load, then$\ h_{ob}$ and$\ R_{L}$ are in parallel. The effective admittance is :

$\ = h_{ob} + \frac{1}{R_{L}}$

If$\ R_{L}$ = 200 kΩ, then the effective admittance:
$\ = 0.5 × 10^{−6} + 0.5 × 10^{−5} = 5.5 × 10^{−6}$mhos

$\ e_{s} = \frac{8.8}{10.1}\left[3 × 10^{−4} + \frac{5.5 × 10^{−6}}{0.98} (1020)\right] × 100 = \frac{8.8}{10.1} (0.60)$ = 0.52%

In this case the slope error becomes large.
$\ e_{s}$ ≈ 0.52 %
(c)  $\ R_{L}$ = 50 kΩ, then the effective admittance
$\ = 0.5 × 10^{−6} + 0.2 × 10^{−4} = 20.5 × 10^{−6}$mhos

$\ e_{s} = \frac{8.8}{10.1}\left[3 × 10^{−4} + \frac{20.5 × 10^{−6}}{0.98} (1020)\right] × 100$

$\ = \frac{8.8}{10.1} (2.16)$ = 1.88%

In this case, the slope error becomes large.
$\ e_{s}$ ≈ 1.88%
The slope error progressively becomes large as$\ R_{L}$ decreases.

Question: 12.1

## Design a relaxation oscillator using a UJT, with VV = 3 V, η = 0.68 to 0.82, IP = 2μA, IV = 1 mA, VBB = 20 V, the output frequency is to be 5 kHz. Calculate the typical peak-to-peak output voltage. ...

The given UJT has the following parameters: [latex...
Question: 12.3

## For the Miller’s sweep shown in Fig. 12.12(a), VCC = 25 V, RC2 = 5 kΩ, RC1 = 10 kΩ. The duration of the sweep is 5 ms. The sweep amplitude is 25 V. Calculate (a) the value of C; (b) the retrace time and (c) the slope error. The transistor has the following parameters: hfe = 80, hie = 1kΩ, ...

(a) \ V_{s} = \frac{V_{CC}}{R_{C1}C_{s}} × ...
Question: 12.4

## The transistor bootstrap circuit in Fig. 12.16(a) has the following parameters, VCC = 15 V, VEE = −10 V, RB = 30 kΩ, R1 = 10 kΩ, RE = 5 kΩ, C1 = 0.005 μF, C3 = 1.0 μF. The input trigger is negative and has an amplitude of 2 V and a width of 60 μs. The transistor parameters are hFE = hfe = 50, ...

Referring to the circuit in Fig. 12.16(a): (a)   S...
Question: 12.5

## Design a transistor bootstrap sweep generator to provide an output amplitude of 10 V over a time period of 1 ms. The ramp is to be triggered by a negative going pulse with an amplitude of 5 V, a pulse width of 1 ms and a time interval between the pulses is 0.1ms. The load resistance is 1 kΩ and ...

Refer to the bootstrap circuit shown in Fig. 12.16...
Question: 12.6

## AUJT has characteristic as shown in Fig. 12.20(a) and the UJT relaxation oscillator is shown in Fig.12.20(b) Find the values of : (a) Sweep amplitude, (b) the slope and displacement errors, (c) the duration of the sweep. and (Assume η = 0.6 and VF = 0.7 V for silicon.) ...

The waveform of the sweep generator is shown in Fi...
Question: 12.7

## Using the characteristic of UJT shown in Fig. 12.21 (a), calculate the values of R, C, R1 and R2 of the relaxation oscillator shown in Fig. 12.21; (b) to generate a sweep with a frequency of 10 kHZ and amplitude of 10V, Tr is 0.5 % of T. ...

Given, $\ f$ = 10 kHz,\ V_{s}[...
Question: 12.8

## For the UJT relaxation oscillator shown in Fig.12.21(c), RBB = 3 kΩ, R1 = 0.1 kΩ, η = 0.7, VV = 2V, IV = 10 mA, IP = 0.01 mA. (a) Calculate RB1 and RB2 under quiescent condition (i.e., when IE = 0). (b) Calculate the peak voltage, VP. (c) Calculate the permissible value of R. (d) Calculate the ...

Given$\ R_{BB}$ = 3 kΩ,\ η[/la...
Question: 12.9

## The bootstrap sweep circuit is shown in Fig.12.22. A square wave whose amplitude varies between 0 and −4 V and duration 0.5 ms is applied as a trigger. a) Calculate all the quiescent state currents and voltages. b) Determine the sweep amplitude, sweep time and sweep frequency. Assume hFE(min) = 30 ...

(a) Current through$\ R_{1}$ is: [lat...
To calculate$\ R_{1}$: Applying KVL t...