PS13201 Datasheet, PDF (7/22 Pages) List of Unclassifed Manufacturers – 500MHz 75dB Logarithmic/Limiting Amplifier

PS13201
a) The device should be mounted on a ground plane, ensuring that the impedance between the ground plane
and ALL the GND pins is kept as low as possible. If a multilayer PCB is used where the ground plane is connected to
the GND pins using through-plated holes (vias), it is essential to ensure that the vias have a very low impedance. ALL
supply decoupling capacitors should be RF chip capacitors whose leads should be kept as short as possible.
b) The RF _VEE connections (pins 3,5,7,11,20,22,24,26) should be connected to a low impedance copper plane. A
two layer PCB should help to achieve this.
c) The RF input (pins 27 and 28) should be driven with a balanced source impedance. One way of achieving this is
to use an isolating BALUN transformer (50Ω UNBALANCED 50Ω BALANCED) connected between the signal
source and the RF input pins. (e.g. Mini circuits TT1–6, TO –75). The device stability is VERY sensitive to an imbalance of the
differential source impedance at pins 27 and 28. Use of a transmission line BALUN though, is NOT recommended.
d) The RF Output connections (pins 9 and 10) should each be loaded with matched impedances ideally
50Ω transmission lines. The RF Output lines leading away from the device should be balanced. Driving highly
reactive SWR loads is NOT recommended as these can encourage device instability, as can an imbalance of the
differential load impedance at pins 9 and 10.
e) The RF Output connections (pins 9 and 10) are DC coupled, and ideally the output pins should be capacitively
coupled to their loads using 1nF capacitors. However the RF Outputs can drive a DC load to GND and a DC offset of
approx. 400mV will exist on each RF Output pin. IT WILL NOT BE POSSIBLE TO DISABLE THE RF OUTPUT
BUFFER UNDER THESE CONDITIONS.
f) The RF output (pins 9 and 10) has a tendency to limit on self noise, particularly at low ambient temperatures (-
55°C), when the RF output buffer is enabled.
NOTE that this will effect the limiting range as the gain of the RF output buffer will reduce as the amount of noise
limiting increases.
If required the limited RF Output can be attenuated using an attenuation network as shown in fig. 9. Under these
conditions the effective RF Output currents will be reduced, allowing the device to operate with a greater margin of
stability. It may be possible to run the device without a BALUN transformer on the RF input if the total output impedance
on the RF Output >> 50Ω , and the attenuation components are mounted as close as possible to the RF Output
connections (pins 9 and 10). The RF input connection could then be configured as in Fig 5.
Data Sheet 210892 issue 3
Plessey Semiconductors Ltd.
Design & Technology Centre, Delta 500, Delta Business Park, Great Western Way, Swindon, UK SN5 7XE
Tel: [phone]
Fax: [phone]
Web: www.plesseysemi.com
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