When is a transistor not a.............

[Fraser, Colin J]

> -----Original Message-----
> From: Dr S Grainger [mailto:steveg at bss10a.staffs.ac.uk]
> Sent: 03 November 1998 11:49
> To: synth-diy at mailhost.bpa.nl
> Subject: When is a transistor not a.............
> 
> 
> Dear All,
> 
> 	Adding my 10p (not on Euros yet !!) to the diode-connected
> 	transistor debate the essence seems to be feedback.
> 
> 	With the base-collector connection made there is a pretty
> 	solid feedback path (the shunt resistor value = 0) This has the
> 	effect of producing a 'diode' with a wider dynamic range than
> 	a 2-terminal device. Also to reduce the resultant 
> circuit's dependance
> 	on the device parameters
> 
> 	I wonder also if it improves the noise performance ?

I have heard - but don't know if this is true - that the diode ladder
filters (EMS Roland etc) were designed to avoid infringement of the Moog
patent on the transistor ladder, as the patent explicitly stated that
transistors were used and not diodes. 
However Roland used transistors configured as diodes (because of the
improved diode operation) and fell foul of the patent anyway.

Anyone confirm or deny this ?

Colin f