A transmission lead of the above type is already known through the article "Exploiting CMOS Reverse Interconnect Scaling in Multigigahertz Amplifier and Oscillator Design", IEEE Journal of Solid-State Circuits, vol. 36, no. 10, October 2001, pp 1480-1488. In order for a transmission lead to be effective, it is desirable that the transmission lead is as loss-free as possible. In, for example, a silicon-based transmission lead, losses are primarily obtained through the capacitive connection to the silicon substrate in combination with the resistance of the lead, which is larger the smaller the structures. There is also an inductive connection that is dependent upon geometric shape and choice of material. Signal losses from these connections to the surroundings are compensated for by means of amplifiers. Losses give rise to noise that is generated via stochastic thermal variations in the resistance of the lead and the surroundings. An exchange of energy with the surroundings is also a source of losses and noise. Ambient noise affects the transmission lead at this connection. At the same time, the transmission lead interferes with the surroundings.

These characteristics and interferences provide a considerable contribution to the phase noise in a feedback transmission lead that we normally call a loop oscillator.

The main object of the present invention is to reduce the capacitive connection to the substrate and the inductive connection to the surroundings. The reduction in the inductive and capacitive connection is achieved by the introduction of complementary leads and by their design, and by the reduction in the capacitive connection by means of differential amplifiers. More specifically, the invention is characterized in that the transmission lead consists of two complementary pairs of leads, incoming and outgoing pairs of leads respectively, where differential amplifiers are connected in parallel in a tight and continuous sequence in close

association with the incoming pair and the outgoing pair and are connected as amplifying elements along the length of the transmission lead in relatively large stretches.

For certain types of applications, it is expedient to use a lead and amplifier group or complex. This applies primarily for non-feedback applications such as, for example, delay elements in connection with signal processing.

For other areas of application, such as for example for loop oscillators, there can be need for more than one of these lead and amplifier groups in order to counteract the occurrence of metastable states. In addition, attention must be paid to connection effects that can arise if, for reasons of space, there is a need to design the transmission lead and its complex as a folded structure.

In this connection, it can be pointed out that transmission leads with complementary leads and differential amplifiers are already known through Swedish patent application 9901450-8.

By introducing complementary leads and differential amplifiers in a transmission lead with distributed amplifiers according to the article above, a transmission lead is obtained in which the capacitive connection is reduced while at the same time the effect of the lead resistance is reduced, resulting in lower lead losses and thereby lower thermally-resistive noise.

According to an advantageous embodiment of the invention, the transmission lead is designed to form a loop oscillator connection. The embodiment is characterized in that the transmission lead is connected in a loop where one complementary lead forms a first loop and the other complementary lead forms a second loop, which loop connection taken as a whole forms a loop oscillator connection. The loop oscillator connection has the advantages relating to low losses that have already been mentioned above.

According to another advantageous embodiment, the transmission lead is designed as a delaying device. The invention is characterized in that the transmission lead is designed as a delaying device by the utilization of the time delay resulting from the interaction between the components in the transmission lead.

According to yet another advantageous embodiment, the invention is characterized in that differential amplifiers are connected in parallel in a tight and continuous sequence in close association with the incoming pair and the outgoing pair and are connected as amplifying elements along the length of the transmission lead in stretches corresponding to at least approximately 1% of the shortest transmitted wavelength.

The lead is suitably designed to be symmetrical with regard to the electrical fields involved.

The transmission lead is advantageously based on a semiconductor substrate, such as silicon.

The invention will be described below in greater detail, with reference to the attached drawings in which : Figure 1 shows an example of a previously-known transmission lead.

Figure 2 shows another example of a previously-known transmission lead.

Figure 3 shows an example of a transmission lead according to the invention.

Figure 4 shows a concrete embodiment of a group or a block comprised in the transmission lead according to Figure 3.

For the purpose of clarification, it should be pointed out that the transmission lead in all the figures is shown as inductive, resistive and capacitive elements, but that in fact it only consists of conductors. These elements are shown only to describe the characteristics of the conductors.

The transmission lead in the form of a loop oscillator shown in Figure 1 is known in principle through the article mentioned in the introduction to the description. The figure shows six amplifiers 1.1-1. 6 connected in parallel.

Between each of the amplifiers, there is a transmission lead 2.1-2. 6 respectively, illustrated with resistive elements 3.1. 1-3.1. k, 3.2. 1-3.2. k,...

3.6. 1-3.6. k, 6.1. 1-6.1. k, 6.2. 1-6.2. k,... 6.6. 1-6.6. k, capacitive elements

4.1. 1-4.1. k, 4.2. 1-4. 2. k,... 4.6. 1-4.6. k, 7.1. 1-7.1. k, 7.2. 1-7.2. k,... 7.6. 1- 7.6. k and inductive elements 5.1. 1-5.1. k, 5.2. 1-5.2. k,... 5.6. 1-5.6. k, 8.1. 1- 8. 1. k, 8.2. 1-8.2. k,... 8.6. 1-8.6. k. k consists of a positive whole number.

Figure 2 shows a known transmission lead with complementary leads and differential amplifiers according to the abovementioned Swedish patent application. The figure shows a loop oscillator with three differential amplifiers 11.1-11. 3 connected in series. Between the differential amplifiers, transmission leads 12.1-12. 3 are connected, illustrated with resistive elements 13.1. 1-13.1. m, 13.2. 1-13.2. m, 13.3. 1-13.3. m, 16.1. 1- 16.1. m, 16.2. 1-16.2. m, 16.3. 1-16.3. m, capacitive elements 14.1. 1-14.1. m, 14.2. 1-14.2. m, 14.3. 1-14.3. m and inductive elements 15.1. 1-15.1. m, 15.2. 1-15.2. m, 15.3. 1-15.3. m, 18. 1. 1-18. 1. m, 18.2. 1-18. 2. m, 18. 3.1- 18.3. m. m consists of a positive whole number.

An example of a transmission lead according to the invention is shown in Figure 3. The transmission lead comprises complementary leads and differential amplifiers arranged according to the following description.

The transmission lead is designed as a loop oscillator and comprises here three groups 20,30, 40 that can have identical constructions. There is, however, no need for these to have an identical construction. Each group comprises preferably a large number of differential amplifiers 21. 1-21. n, 31. 1-31. n, 41. 1-41. n. Lead sections 22, 22', 23, 23', 32, 32', 33,33', 42, 42', 43,43'are illustrated at the input and output side of the differential amplifiers. For the lead sections 22, 22', 23,23'there are resistive components 22.1-22. n, 23.1-23. n, 22'. 1-22'. n, 23'. 1-23'. n, capacitive components 24.1-24. n, 25. 1-25. n and inductive components 26.1-26. n, 27.1-27. n, 26'. 1-26'. n, 27'. 1-27'. n. Elements are doubled and a complementary transmission lead is constructed where one complementary lead's components are designated without prime symbol and the other complementary lead's components are designated with prime symbol, with one complementary transmission lead being connected to the differential amplifiers'first inputs in the group, while the other complementary lead is connected to the differential amplifiers'second inputs in the group. n denotes an arbitrary positive whole number, and can stand for a relatively large number, for example of the order of a hundred.

The groups 30 and 40 are constructed in a corresponding way to that described above for the group 20.

By dividing the transmission lead shown in Figure 3 between two groups, for example between groups 20 and 40, the lead can be used as a delaying device with, in this example, the input of group 20 as the input of the delaying device and the output of group 40 as the output of the delaying device.

Figure 4 shows a group, for example the group 40 according to Figure 3, implemented in an integrated circuit in silicon. Components that correspond to those in Figure 3 have been given the same reference numerals in Figure 4. As shown in Figure 4, the differential amplifiers 41.1- 41.4 are connected in parallel in a tight and continuous sequence and are each divided into two symmetrical parts which have been given the same reference numeral.

The invention is not limited to the embodiments shown in the above as examples, but can be modified within the framework of the following patent claims.