In radio astronomy, the SIS receivers (for a review see, e.g.,
[38]), providing the analog input signals require helium
cooling. This fact alone, in contrast to many other possible
applications of RSFQ digital technology, levels the ground when we
compare currently used semiconductor correlators to their possible
RSFQ counterparts. Another important observation is that the two main
parameters of the existing radio astronomy correlators/spectrometers
- the signal bandwidth and frequency resolution are already close to
their limits. The maximum attainable signal bandwidth is presently
limited by HEMT amplifiers to around several GHz. The best
achievable frequency resolution is determined by natural line width of
the radio signal which typically is close to 
. However, RSFQ
correlators can offer two important advantages. First, hardware
complexity (= cost) of a broadband correlator decreases rapidly with
clock speed. From this consideration, the RSFQ digital (auto- and
cross-) correlators running at 
clock speeds will
definitely outperform the existing analog correlators when the level
of 
lags is reached. With 
lags they will beat
the digital as well as the (very complex and costly) analog-digital
systems. In the 
- 
HYPRES' technology
[7] a 400-channel correlator can fit on a single 
chip.
Another important advantage of an RSFQ correlator arises when we
consider space-borne applications where reduction in power dissipation
could be of crucial importance. In this thesis we study the problem of
further lowering of power dissipated by RSFQ devices and provide ample
experimental evidence demonstrating that power dissipated by an RSFQ
correlator can be reduced to below 
(at 
) per
channel for clock speeds up to 
. Even with a very
inefficient cryocooler (say, 
) this translates into only
milliwatt per channel at room temperature and is two orders
of magnitude better than the best semiconductor correlators. It is
important to note that with currently used value of bias voltage
(close to 
) dc power dissipation in the same RSFQ circuit
would have been 20-30 times higher and total power requirements -
only several (or up to ten, depending on a cryocooler) times better
than in a semiconductor device.
The combination of unusually low power dissipation with very high clock speeds can also pave the road for many other possible applications of RSFQ digital technology. In some cases, such as Petaflops-scale computing (see, e.g, [39]) this combination offers a decisive advantage over any other technology. Numerical estimates done in [3] clearly show how crucial is low power requirement for the Petaflops project.