KH207

DATA SHEET

REV. 1A January 2004

5

Figure 4: Active Current Limit Circuit (50mA)

Controlling Bandwidth and Passband Response

In most applications, a feedback resistor value of 2k

Ω

will provide optimum performance; nonetheless, some

applications may require a resistor of some other value.

response peaking, which may lead to instability).

Conversely, large values of feedback resistance tend to

roll off the response.

The best settling time performance requires the use of an

external feedback resistor (use of the internal resistor

results in a 0.1% to 0.2% settling tail). The settling

performance may be improved slightly by adding a

capacitance of 0.4pF in parallel with the feedback

resistor (settling time specifications reflect performance

with an external feedback resistor but with no external

capacitance).

Thermal Model

Noise Analysis

Approximate noise figure can be determined for the

KH207 using the Equivalent Input Noise plot on page 3

and the equations shown below.

Figure 5: Noise Figure Diagram and Equations

(Noise Figure is for the Network Inside this Box.)

Driving Cables and Capacitive Loads

When driving cables, double termination is used to

prevent reflections. For capacitive load applications, a

small series resistor at the output of the KH207 will

improve stability and settling performance.

Transmission Line Matching

One method for matching the characteristic impedance

appropriate resistor at the input or output of the amplifier.

Figure 6 shows typical inverting and non-inverting circuit

configurations for matching transmission lines.

Figure 6: Transmission Line Matching

Non-inverting gain applications:

loading caused by the transmission line,

or by parasitics.

KH207

+

-

F

R

R

R

kT

i

V

R

Ri

RA

where R

RR

RR

A

R

R

s

n

s

n

n

p

f

i

pv

p

sn

sn

v

f

g

=+

+

⋅

+

+





































=

+

=+

10

1

4

1

2

2

2

22

22

log

;

Q3

(2N3906)

14.3k

Ω

Q4

(2N3904)

0.01

ΩF

0.01

ΩF

12

Ω

Q1

(MJE170)

Q2

(MJE180)

12

Ω

to pin 10

to pin 12

K

(% duty cycle)

θ

65°C/W in still air without a heatsink.

35°C/W in still air without a Thermalloy 2268.

15°C/W in 300ft/min air with a Thermalloy 2268

(Thermalloy 2240 works equally well.)

+

-

17.5

100

°C/W

100

°C/W

KH207

+

-

+

-