"Not sure why you perceive it as having low voltage gain" Trade-offs are often made in the pursuit of other of goals at the cost of sheer overall "gain" - such as achieving a usually elusive _low noise figure_ and circuit stability - factors closely tied to the physics and structure of the devices (tubes) that were used in the time frame when the 'cascode' configuration was 'discovered' and the term coined. In today's world those goals are much easier to meet but were a bonafide _challenge_ fifty years ago given the devices and technology available ... I think the quotes I excerpted from Skolnick said it best in this regard. "Originally used quite widely in the RF stages of TV tuners," We might find out the origins of the 'cascode' circuit configuration if we were to research this subject in the MIT "Rad Lab Series" (meaning it was probably first used in RADAR apps beginning in the forties and prior to use in TV tuners) ... Jim ----- Original Message ----- From: "Alan B. Pearce" To: Sent: Wednesday, May 29, 2002 3:23 AM Subject: Re: [EE]: Cascoded? > >The 'cascode' configuration has other goals like > >improved bandwidth and lower noise figure as contrasted > >to simply increasing the gain, verily, voltage (and even > >current) gain in a cascode configuration is _lower_ > >than other configurations ... > > Not sure why you perceive it as having low voltage gain, one of my memories > of the use of this configuration is to have a low voltage swing input drive > a high voltage transistor in the output stages of oscilloscopes for > deflection plate drive. > > The original configuration was designed for RF use when the devices > available had high miller feedback effects. The use of two devices in the > cascode configuration resulted in much better output to input isolation, > allowing much higher gain. Originally used quite widely in the RF stages of > TV tuners, back in the days when these were built with vacuum tubes, but I > imagine the configuration was used long before that. > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.